This invention generally relates to circuit breakers having a three position actuator or handle and an auxiliary switch to provide remote indication of the circuit breaker condition. It more specifically relates to split case circuit breakers having a collapsible link and a sub-assembly that selectively engages the auxiliary switch.
The use of an auxiliary switch in the lower or bottom wall of a split case circuit breaker is well known. See for example U.S. Pat. No. 4,760,226, where a lever is pivotally supported inside the case for moving the plunger of the auxiliary switch when the movable contact arm is in a contact-closed condition. In U.S. Pat. No. 3,742,403 an auxiliary switch is provided in the circuit breaker side wall, and is operated by a lever that is engaged by a knee portion of the collapsible link coupling the movable contact arm and the actuator. This general concept is incorporated in the present disclosure by a pair of uniquely joined plastic levers that selectively operate an auxiliary switch in the bottom of the case.
Another known feature for a split case circuit breaker is to provide for visual indication of the breaker mechanism""s tripping device, that is, to visually show whether the contacts have opened due to an electrical overload. U.S. Pat. No. 3,955,162 shows such a feature in a breaker mechanism that provides for collapsing of the collapsible link whenever the circuit breaker mechanism has been electro-magnetically tripped. Circuit breaking movement of the handle/actuator is interrupted at a xe2x80x9ccenterxe2x80x9d position by a leaf spring that is carried by the handle/ actuator and that will engage the case when the collapsible link is collapsed. This ""162 patent does not suggest another approach to stopping the handle or actuator at a xe2x80x9ccenterxe2x80x9d position.
A prior art breaker of the type having a collapsible link that collapses whenever the mechanism is electro-magnetically tripped employs a metal lever to operate an auxiliary switch from the collapsed link. U.S. Pat. No. 4,760,226 shows such a metal lever mounted in the metal frame of the mechanism. The prior art does not, however, show or suggest that this feature can be achieved with a non-metallic plastic lever that is not pivotally mounted to the frame. The prior art metal lever of the ""226 patent is supported in the metal frame that supports the breaker mechanism creating an electrically conductive component close to the contacts and to the arc suppresser plates. The advantages of providing a plastic lever outside of and apart from the metal frame are important to meet present day dielectric criteria for circuit breakers generally.
While split case circuit breakers incorporating an auxiliary switch are known in the art, the auxiliary switch is generally designed to be normally-closed. That is, when these prior art breakers are manually switched ON or OFF, the auxiliary switch circuit remains closed. When an electrical fault occurs that trips these prior art breakers, the auxiliary switch changes to the switch-open condition. It is an object of this invention to disclose a circuit breaker that operates in the reverse manner. The auxiliary switch of the present invention remains in the normally-open condition when the circuit breaker is manually switched ON or OFF, and subsequently moves to the switch-closed condition when the circuit breaker undergoes an electrical fault. The present invention also maintains the auxiliary switch in the switch-open condition when the breaker is reset, but not when the actuator is manually moved from the ON to OFF position.
In a product currently marketed by the assignee hereof, Carling Technologies Inc., of Plainville, Conn., U.S.A., an auxiliary switch is operated by a bellcrank or L-shaped plastic lever that has one arm that acts as the auxiliary switch lever, and a second arm that is selectively engaged by the collapsible link mechanism to provide remote readout indication for the circuit breaker (e.g. tripped or not tripped only). Carling Technologies sells this unit as its xe2x80x9cC-Series Trip Alarm Circuit Breakerxe2x80x9d.
In accordance with the present invention, a circuit breaker assembly is provided comprising a housing, an electrical contact mounted on a contact arm that is moveable between contact-open and contact-closed conditions and biased to the contact-open condition, and an actuator selectively moveable between ON and OFF positions. The circuit breaker further includes a toggle mechanism that couples the actuator to the contact arm such that when the actuator is moved to the ON position, the contact arm is moved to the closed-contact condition. A trip subassembly is further included that has an auxiliary switch lever and a trip lever hingedly connected to each other, and an auxiliary switch changeable between switch-open and switch-closed conditions. This auxiliary switch is biased to the switch-open condition and is further connectable to a remote indicator. The auxiliary switch lever acts on the auxiliary switch when the actuator is moved either from the OFF to ON or from the ON to OFF positions.
The following describes general aspects of the preferred embodiment. When the circuit breaker actuator is moved to the ON position, the contact arm acts through the auxiliary switch lever to place the auxiliary switch in a switch-open condition. When the actuator is then moved to the OFF position, pressure on the auxiliary switch lever from the contact arm is released and the circuit breaker contacts open, but the trip lever holds the auxiliary switch lever against the auxiliary switch to keep it in the switch-open condition. Conversely, when the circuit breaker trips, the trip lever is mechanically pushed away by linkage connected to the actuator. The auxiliary switch lever cannot itself overcome the bias of the auxiliary switch, which consequently changes to the switch-closed condition. This switch-closed condition is maintained even when the actuator is reset (i.e. manually moved from the TRIPPED position back to the OFF position).